The present invention relates to seals, and more particularly to segmented lift-off seal assemblies for sealing about rotatable members.
Circumferential lift-off seal assemblies are generally known and include two or more arcuate segments coupled together to form an annular seal disposed about a rotatable member, such as a shaft or a runner/sleeve mounted to the shaft. The inner surface of the seal engages the outer surface of the rotatable member in a static state and the seal is configured to “lift” or displace radially-outwardly from the rotatable member during dynamic operation. Typically, lift ramps or pads are provided on the seal inner surface, or grooves are provided on the outer surface of the rotatable member, such that fluid is pressurized by the ramps or grooves to cause the outward displacement of the seal segments. However, in high-pressure applications, the lifting force generated by the ramps or grooves may either be insufficient to displace the seal body from the shaft, or delay the lifting of the seal segments, such that the seal becomes damaged or worn by sliding contact with the rotatable member.